Endangered sea otters in Japan may soon ‘disappear’ from aquariums

With his soft brown fur and lithe body, sea otter Riro twirls in the water, claps his paws and floats.

Riro, who celebrated his 16th birthday in March, is just one of three remaining sea otters in Japan’s aquariums.

The other two are female: Kira, 15, and May, 18. They live at Toba Aquarium in Mie Prefecture, while Riro lives at the Marine World Uminonakamichi in Fukuoka.

But they are now too old to breed.

Male sea otters live between 10 and 15 years, while females live between 15 and 20 years, according to the Centre for Biological Diversity in the US.

Overhunting for their fur has depleted the global population of the species, and the international trade was strictly regulated under the Washington Convention.

Sea otters were listed as endangered by the International Union for Conservation of Nature in 2000. In 1998, imports of sea otters to Japan from the United States ceased, and from Russia in 2003.

Sea otters in Japan

In 1982, Izu Mito Sea Paradise in Shizuoka Prefecture became the first aquarium in Japan to start breeding sea otters, according to the Japanese Association of Zoos and Aquariums.

The species became a huge draw to visitors and became an attraction on its own.

At the peak year in 1994, there were 122 sea otters in 28 aquariums in Japan. In 2000, there were 88 sea otters in aquariums, but their number fell from 30 in 2011 to 10 in 2017.

The Japanese Association of Zoos and Aquariums said that the number shrank due to difficulties with nursing and breeding.

In 2021, the female of the only mating pair died, dashing hopes for domestic breeding.

Mr Yoshihiro Ishihara, who is responsible for sea otter breeding at Toba Aquarium, was quoted in a Kyodo report as saying that that “it is not clear” why the animals have had difficulty mating.

However, he suggests that one possibility is that the males’ reproductive capacity has declined.

As male adult otters attack or even try to mate with their own offspring, they are generally kept in separate tanks from others, and “perhaps their instincts have waned” as a result, he said.

Nonetheless, they still continue to draw visitors to the aquariums.

“They are cute and relaxing to watch,” said Ms Megumi Iha, 29, at the Toba Aquarium.

Ms Nao Matsuda, 46, said: “I would feel sorry for children if there were no more sea otters in aquariums.”